Fuel injection device



April 23, 196s l.. T. MEKKES 3,379,374

FUEL INJECTION DEVICE Filed Aug. 22, 196e HTTOR/VEY United States Patent0 3,379,374 FUEL INJECTION DEVICE Lee T. Mekkes, Grandville, Mich.,assignor to General Motors Corporation, Detroit, Mich., a corporation ofDelaware Filed Aug. 22, 1966, Ser. No. 574,118 6 Claims. (Cl. 239-90)This invention relates to fuel injection devices of the type utilizedfor the injection of fuel into the cylinders of internal combustionengines and more particularly to improved valve arrangements for suchdevices.

In its more particular aspects, the invention relates to an improvedvalve and nozzle arrangement for unit fuel pump injectors of the typeshown in United States Patent No. 3,006,556 Shade et al.

While unit injector assemblies of the general type shown in theabove-mentioned patent have given very satisfactory service in a widerange of engine applications,

the fact that the needle valve is carried directly in the spray tipmember makes it necessary to replace this complete unit whenever wear ordamage to either portion of the unit occurs. In addition, the tiow pathof the fuels from the plunger body to the spray tip is relativelyindirect being through a series of small passages, both straight andannular, bypassing the needle valve and its biasing spring assembly.

The present invention proposes an improved valving and injector tiparrangement which provides a nearly direct axial flow of fuel throughthe center of the valve and nozzle portions to the spray tip, therebypermitting larger passages and offering less restriction to flow.Additionally, the arrangement separates the needle valve assembly fromthe spray tip so as to permit replacement or reconditioning of eitherone of the members separately should the occasion arise, therebyreducing the cost of servicing or reconditioning the injector assembly.

These and other advantages of the invention will be better understoodfrom the following description of a preferred embodiment selected forpurposes of illustration, having reference to the drawing, wherein:

FIGURE 1 is a longitudinal, sectional View through a unit fuel pumpinjector having an improved nozzle and valving arrangement according tothe invention;

FIGURE 2 is an enlarged view showing the nozzle and valving arrangementof FIGURE 1; and

FIGURE 3 is a pictorial view showing certain features of a check valvebody for use with the preferred embodiment of FIGURES 1 and 2.

Referring now in more detail to the drawing, and in particular to FIGUREl, the upper portion of the unit is conventional and comprises a housing11 in which a plunger 12 is reciprocable. Forming an extension of andthreaded to the lower end of the housing 11 is a nut 13 within which issupported a bushing 14, forming the pump cylinder for the plunger 12. Anannular space 16 surrounding the bushing 14 within the nut is suppliedwith fuel via passages 17 in the housing from an external fuelconnection 18.

The plunger has the usual external metering groove 19 adjacent its lowerend by which opening and closing of ports 21 and 22 in the bushings arecontrolled during each downward stroke of the plunger to deliver apredetermined volume of fuel through the lower open end 23 of thebushing for injection into the engine (not shown) via the spray orificesZ4 at the bottom of the unit. Other details of the upper or pump part ofthe unit are not important to the present invention, and are common toconstruction shown and described in such prior patents as Engel, Jr.2,951,643 and Teichert 2,898,051, hence will not require furtherdescription here.

Patented Apr. 23, 1968 ice As is best shown within the nut 13 in FIGURE2, and clamped between the shoulder 26 in its lower end and the lowerend face 27 of the bushing 14 are a check valve body 2S, spacer 29 and aspray nozzle 31. These members are formed with a small annular clearance32 between them and the nut 13 to assure their being tightened intosealing engagement upon tightening of the nut 13 on the housing 11.

The lower end face 27 of the bushing acts as a closure seat for acircular check valve disc 33. This disc is disposed in a recess orcavity 34 formed in the top portion of the check valve body 28. Thesides of the cavity 34 extend laterally beyond the extremities of theopen end 23 of the bushing and serve to loosely guide the disc 33. Acentral annular protuberance 36 is formed in the bottom of the cavity 34and serves as a stop to limit opening travel of the check valve disc 33.A central opening 37 extends axially through the check valve body andconnects with the recess 34 through radial grooves 38 formed in thesurface of stop 36 so that communication is provided between the recessand opening in all positions of the valve disc 33.

Within spacer 29 is a cylindrical cavity 39 in which are disposed avalve seat member 41, needle valve 42 and coil spring 43. The valve seatmember includes an axial passage extending therethrough which isseparated into larger and smaller diameter portions 44 and 46respectively by a frusto-conical valve seat 47 intermediate the ends ofthe passage. The valve seat member 41 is reciprocably movable withincavity 39 and is biased upwardly by the surrounding spring 43 actingagainst nozzle 31 and an annular shoulder 48 of the seat member suchthat the valve seat 47 is forced into engagement with the conical end 49of the needle valve 42. This forces the other end 52 of the needle valveinto sealing engagement with the lower face S3 of the check valve body.

The needle valve 42 includes an axial bore 54 which terminates short ofits lower end 49 and connects through a cross-drilled bore 55 in areduced diameter portion of the needle valve with an annular chamber S6dened between the lower end of the needle valve and a slight enlargementof the larger diameter portion 44 of the passage through valve seatmember 41. The remainder of the larger diameter passage portion 44 isclosed by engagement with the outer surface of needle valve 42. Thisengagement is preferably a lapped tit to provide for reciprocatingmovement of seat member 41 with respect to the needle valve withoutpermitting substantiai leakage between the lapped surfaces of themembers. Spacer 29 includes a drain opening 57 which permits the escapeof fuel leaking into cavity 3-9 by escape through the annular clearance32 into the annular space 16 thereabove.

On its lower end, valve seat member 41 carries a cylindrical extension58. The extension is reciprocably received, preferably as a lapped t, inthe enlarged upper portion 59 of a central bore 6=1 which extends nearlythrough spray nozzle 31 and connects with spray orifices 24 in the spraytip portion 62 of the spray nozzle. An annular stop surface 63 surroundsthe extension and is adapted to engage the upper face 64 of the spraynozzle and limit opening of the needle valve.

In operation, reciprocating action of the plunger 1-2 delivers mete-redamounts of fuel intermittently through lower end 23 of the bushing 14.The fuel passes around valve disc 33 through grooves 38 and opening 37into bore 54 of the needle valve and cross-bore 55 to annular chamber56. As the pressure in the chamber 56 increases, the differential areabetween the upper and lower ends of the chamber causes a downward forceupon valve seat member 41 which, at a predetermined pressure, overcomesthe force of spring 43 and moves seat member 41 downwardly intoengagement with the upper face 64 of the nozzle member 3-1. At the sametime, upward pressure of 4the fuel upon needle valve 42 holds the valvein its fixed position against check valve body 28. Thus valve seat 47moves away from the end 49 of the valve member and permits fuel to owfrom chamber 56 through small diameter passage portion 46 and centralbore 61 of the nozzle out through spray orices 24.

When the delivery of fuel is cut olf by action of the plunger,-the fuelpressure in chamber 56 decreases until, at a predetermined pressure,spring 43 again lifts the valve seat member 41 until seat 47 engages end49 of the needle valve cutting off further flow of fuel to the nozzle.If for any reason an undue surge of pressure occurring in the cylinderwhile the needle valve is open should attempt to cause fuel to flow inreverse through the nozzle and valve assembly, this action will seatdisc valve 3'3 against the lower end face 27 of plunger 14, preventingany backflow of fuel to the bushing 14.

Having disclosed in det-ail a preferred embodiment of my invention, itis apparent that many variations within the spirit and scope of theinvention will occur to those skilled in the art and it is thereforeintended that the invention not be limited except by the language of thefollowing claims.

lI claim:

l1. A fuel injection device comprising a stationary nozzle having acentral bore and a dis charge orifice at one end of said bore,

a reciprocable valve seat member having an axial passage with a valveseat intermediate its ends and separating said passage into larger andsmaller diameter portions, said smaller diameter portion connecting withsaid nozzle bore,

a stationary needle valve having a body portion sealingly engaging saidlarger diameter portion, an end of smaller diameter than said bodyportion and engageable by said valve seat and an axial bore terminatingshort of said end and connecting with an annular chamber formed betweensaid needle valve and the larger diameter portion of said seat memberpassage adjacent said valve seat and biasing means urging said valveseat member in a direction to engage said valve seat with said valvemember end,

said biasing means being adapted to yield to the force caused bydelivery of a predeterrmined pressure o'f fuel to .said annular chamberwhereby to move said valve seat away from said needle valve end and pernmit fuel to iiow past said valve seat and axially into said nozzle.

2. The device of claim 1 and further including stop means on said valveseat member and engageable with said nozzle to limit the travel of saidvalve seat away from said needle valve and assist prompt re-engagementof said valve seat and valve upon reduction of the fuel deliverypressure to a predetermined value.

3. The device of claim 2 wherein said valve seat member includes acylindrical extension surrounding said pas- 6 sage, said extension beingsealingly received in an enlarged portion of said nozzle bore to preventsubstantial leakage of fuel from between said nozzle and said valve seatmember.

4. The device of claim 1 and further including check valve meansupstream of said stationary needle valve and arranged to permit thesupplying of fuel to said needle valve but to prevent the return ow offuel from said needle valve to the source of supply.

5. The device of claim 4 `wherein said check valve means includes a fueldelivery member having an end and a fuel delivery opening locatedcentrally thereof,

a valve body between and engaging said fuel delivery member and saidneedle valve and having a central opening connecting said fuel deliveryopening with said needle valve bore,

a flat valve disc received in a recessed portion of said valve body andengageable with the end of said fuel delivery member to prevent thereturn iow of fuel thereto and 1 an annular stop surrounding the openingin the recessed -portion of said valve body and engageable by said valvedisc, said stop having radial grooves in its disc engaging Surface toprovide a path for fuel to bypass said valve disc when in engagementwith said stop.

6. A fuel injection device comprising a stationary nozzle having acentral bore,

a reciprocable valve seat member having an axial passage connecting withsaid nozzle bore and a valve seat surrounding said passage,

a stationary needle valve having an end engageable by said valve seat toshut olT ow through said passage, said needle valve having an axial boreterminating short of said end and connecting with an annular chamberpartially defined by said valve seat member and biasing means urgingsaid valve seat member in a direction to engage said valve seat withsaid valve member end,

said chamber defining surfaces of said valve seat member being arrangedsuch that fuel pressure in said chamber exerts a force on said valveseat member opposing the force of said biasing means whereby upondelivery of a predetermined pressure of fuel to said chamber throughsaid needle valve, said EVERETT W. KIRBY, Primary Examiner.

10/ 195 1 Italy.

1. A FUEL INJECTION DEVICE COMPRISING A STATIONARY NOZZLE HAVING ACENTRAL BORE AND A DISCHARGE ORIFICE AT ONE END OF SAID BORE, ARECIPROCABLE VALVE SEAT MEMBER HAVING AN AXIAL PASSAGE WITH A VALVE SEATINTERMEDIATE ITS ENDS AND SEPARATING SAID PASSAGE INTO LARGER ANDSMALLER DIAMETER PORTIONS, SAID SMALLER DIAMETER PORTION CONNECTING WITHSAID NOZZLE BORE, A STATIONARY NEEDLE VALVE HAVING A BODY PORTIONSEALINGLY ENGAGING SAID LARGER DIAMETER PORTION, AN END OF SMALLERDIAMETER THAN SAID BODY PORTION AND ENGAGEABLE BY SAID VALVE SEAT AND ANAXIAL BORE TERMINATING SHORT OF SAID END AND CONNECTING WITH AN ANNULARCHAMBER FORMED BETWEEN SAID NEEDLE VALVE AND THE LARGER DIAMETER PORTIONOF SAID SEAT MEMBER PASSAGE ADJACENT SAID VALVE SEAT AND